Journal of Biological Chemistry
Volume 287, Issue 9, 24 February 2012, Pages 6735-6742
Journal home page for Journal of Biological Chemistry

Protein Structure and Folding
The Molecular Chaperone gp96/GRP94 Interacts with Toll-like Receptors and Integrins via Its C-terminal Hydrophobic Domain*

https://doi.org/10.1074/jbc.M111.309526Get rights and content
Under a Creative Commons license
open access

The structural basis for molecular chaperones to discern misfolded proteins has long been an enigma. As the endoplasmic reticulum paralogue of the cytosolic HSP90, gp96 (GRP94, HSP90b1) is an essential molecular chaperone for Toll-like receptors (TLRs) and integrins. However, little is known about its client-binding domain (CBD). Herein, we provide genetic and biochemical evidence to definitively demonstrate that a C-terminal loop structure, formed by residues 652–678, is the critical region of CBD for both TLRs and integrins. Deletion of this region affects neither the intrinsic ATPase activity nor the overall conformation of gp96. However, without it, the chaperoning function of gp96 collapses. We also find a critical Met pair (Met658-Met662) for the folding of integrins but not TLRs. Moreover, we find that the TLR binding to gp96 is also dependent on the C-terminal dimerization domain but not the N-terminal ATP-binding pocket of gp96. Our study has unveiled surprisingly the exquisite specificity of gp96 in substrate binding and suggests a manipulation of its CBD as an alternative strategy for targeted therapy of a variety of diseases.

Endoplasmic Reticulum (ER)
Hsp90
Integrins
Molecular Chaperone
Toll-like Receptors (TLR)
HSP90b1
gp96
grp94
Innate Immunity
Unfolded Protein Response

Cited by (0)

*

This work was supported, in whole or in part, by National Institutes of Health Grants AI070603, AI077283, and HL100556 (to Z. L.), and by the Flow Cytometry Shared Resource, Hollings Cancer Center, Medical University of South Carolina (P30 CA138313).

This article contains supplemental Table S1 and Figs. S1 and S2.